1. Field of Invention
The present invention relates to a method for preparing porous fabrics and a device thereof. More particularly, the present invention relates to a method for preparing a porous activated carbon fabric with uniform nano-pore distribution.
2. Description of Related Art
Activated carbon is a porous material with good absorption, electrical conduction, and regeneration characteristics that is applied to the products of environmental protection, industrial purpose, and high tech industrial purpose. Activated carbon is used in gauze masks, protection cloths, and gas masks for chemical, medical, and military purposes; or general textile products, water purification, and liquid waste treatment.
Activated carbon is generally divided into granulate activated carbon, activated carbon powder and activated carbon fiber. Granulate activated carbon and activated carbon powders are conventional types made by carbonizing the coconut shell, brown coal, peat or other such material at high temperature. The manufacturing processes of both the above-mentioned activated carbons are low cost and the materials are easy to obtain, but the products exhibit poor absorption characteristics and have high impurity content.
Activated carbon fiber (fabric) includes cellulose-based, phenol resin-based, pitch-based, and polyacrylonitrile-based (PAN) activated carbon fiber wherein the cellulose-based, phenol resin-based, and pitch-based activated carbon fiber exhibit poor mechanical properties. The PAN-based activated carbon fiber has advantages over the other activated carbon fibers is reasonable cost and good mechanical properties that provide future development potential.
An activated carbon fabric is generally manufactured by employing a PAN-oxidized filament or yarn as a raw material to undergo an activation process and a carbonization process to form an activated carbon filament (or yarn), and the activated carbon filament (or yarn) further forms an unwoven fabric by conventional unweave method. The activation process is preformed by chemical activation or physical activation process. The chemical activation treats the PAN-based oxidized fiber by using chemicals such as ZnCl2, H3PO4, KOH, or K2S at a low working temperature. The disadvantages of the chemical activation process are lower purity of activated carbon and environmental pollution from the steps used to wash the chemicals away. The physical activation process employs oxygenated gas to activate the PAN-based oxidized fiber, and the disadvantages include consumption of more energy to maintain a high working temperature and high tar content.
Recently, the PAN-based oxidized fabric of the fireproof cloth has been employed to form the porous activated carbon fabric. A water-containing carbon dioxide gas made by passing the carbon dioxide through water was an activating gas for activating the PAN-based oxidized fabric in a high temperature chamber to form a PAN-based activated carbon fabric. However, controlling the saturation steam of the carbon dioxide is difficult and causes different pore distributions in the activated carbon fabric. Therefore the quality of the product is unstable.
For the forgoing reasons, there is a need for developing a more convenient and effectively process to solve the problem of various pore distributions and the unstable quality of PAN-based activated carbon fabric.